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Bandyopadhyay, Asish
- Welding of Acryalics Using Laser Beam:An Experimental Investigation
Authors
1 Department of Mechanical Engineering, Kalyani Government Engineering College, Kalyani-741235, West Bengal, IN
2 Department of Mechanical Engineering, Jadavpur University, Kolkata-700 032, IN
Source
Indian Welding Journal, Vol 47, No 4 (2014), Pagination: 23-23Abstract
Laser beam welding (LBW) uses high energy density beam making it suitable for welding of wide category of materials. As energy density around the focal point of laser beams is quite high, this technique is being increasingly used in the fabrication industry. Since laser beams follow the principle of optics, it can be easily regulated by selecting appropriate lenses. In this paper, a report on the experimental work involving laser beam welding (LBW) is presented where lap joints of two acryalic (polycarbonate) flats-one opaque and the other transparent, are tried to make. Laser beam passes through the transparent piece of plastic flat, and is focused on to the opaque flat around the interface region. Laser beam gets absorbed in the opaque flat in the interface region and generates heat energy causing local melting, and subsequent welding of both the flats. This method is named as through transmission laser welding. The bonding between the two components is likely to occur by interpenetration of molecular chains in the area that is promoted by fluidity of acrylic during welding. Process parameters such as clamping pressure and current are varied at some selected scanning speeds to explore the appropriate condition to obtain sound, strong weld joint within the experimental domain. The laser has a repetitive operating current less than 60 A with pulse frequency of 0.25-10 kHz. The used 30 W laser system is having spectral width of 1.69 nm, beam divergence of less than 0.20 N.A. and beam diameter of 800 urn with a wavelength of 809.40 μn. Scanning speed of 240,280,320 and 360 mm/min, current flow of 25,28,31 and 34 A, and clamping pressure of 20, 30,40 and 50 Kg/cm2 are chosen in this work. Sound welded joint between transparent and opaque acryalic components with high weld strength above 8 MPa is obtained under scanning speeds of 280 and 360 mm/min and 20 Kg/cm2 clamping pressure with weld current setting of 28, 31 and 34 A. Suitable heat input to the weld interface may have resulted in this observation. Therefore, these conditions may be recommended to apply to obtain large weld strength.
- An Experimental Investigation on Laser Beam Welding of Acrylics
Authors
1 Department of Mechanical Engineering, Kalyani Government Engineering College, Kalyani-741235, West Bengal, IN
2 Department of Mechanical Engineering, Jadavpur University, Kolkata-700 032, IN
Source
Indian Welding Journal, Vol 47, No 4 (2014), Pagination: 75-80Abstract
Laser beam welding (LBW) is nowadays increasingly used in the fabrication industry due to some of its distinct advantages. LBW offers high energy density around its focus thereby making it well suited for welding of certain category of materials that are considered difficult-to-weld. Since the laser follows the principles of optics, it is easy to regulate the laser beam by selecting appropriate lenses. In the present work, laser beam welding (LBW) is carried out to make lap joint of two acrylic flats- one opaque and the other transparent. Laser beam passes through the transparent piece of plastic flat and is focused on to the opaque flat around the interface region. Laser beam gets absorbed in the opaque flat in the interface region and generates heat energy causing local melting, and subsequent welding of both the flats. Clamping pressure is varied four times, and two levels of current flow and scanning speeds are set to find out a condition corresponding to sound, strong weld joint within the experimental domain. Good quality joint between transparent and opaque acrylic components with high weld strength of 8.33 MPa is obtained under 280 mm/min scanning speed and 2 MPa clamping pressure with 34 A weld current set, and hence, this condition may be recommended to apply to obtain enough weld strength.Keywords
Laser, Welding, LBW, Laser Beam Welding, Acrylic, Plastic Welding.- Research Trends for Simulation Modeling, Parametric Optimization of Bead Geometry and Mechanical-Metallurgical Characteristics of Submerged Arc Weld: Review and Future Scope
Authors
1 Department of Mechanical Engineering, National Institute of Technology, Rourkela, Orissa, IN
2 Department of Mechanical Engineering, Jadavpur University, Raja S. C. Mallik Road, Kolkata, IN
Source
Indian Welding Journal, Vol 42, No 3 (2009), Pagination: 43-57Abstract
Submerged arc welding (SAW) is a useful metal joining process in fabrication industry. The process is characterized by the use of granular flux blanket that covers the molten weld pool during operation. This arrangement avoids atmospheric contamination to the weld bead, facilitates slower cooling rate and, thereby, enhancing mechanical-metallurgical characteristics of the weldment. It is well-known that several process control parameters influence (directly or indirectly i.e. factorial interaction) various quality features of the weldment. Work, to a far extent, has already been done to study the effects of the parameters (as well as their interactions) like voltage, current, electrode stick-out, wire feed rate, traverse speed etc. on bead geometry, weld quality and performance attributes in terms of mechanical-metallurgical-chemical characteristics of the weld produced by submerged arc welding on structural steel. But the search is still being continued and results thereof are being reported which indicate the necessity of acquiring in depth knowledge in this regard. Control of the above parameters, in a more precise manner, can essentially improve weld quality, enhance the possibility of increased deposition rate and economize the overall process. In consideration of the above, the present reporting outlines the trends of research on various aspects of prediction-modeling, simulation and optimization of submerged arc weld. The application feasibility including relative merits as well as demerits of various modeling-optimization methodologies proposed and adopted by previous investigators in examining the process behavior of SAW has been illustratively highlighted. It is felt that the information provided in this reporting may definitely give an insight to the young researchers especially to identify the ischolar_main locus of the past research progressed in the said field and, thereby, helping them in selection of proper direction of work towards value added outcome for the benefit of both academic fraternity as well as industry personnel.
Keywords
SAW, Modeling, Simulation, Optimization.- Submerged Arc Welding With a Mixture of Fresh Flux and Fused Slag-Modeling with Quadratic Response Surface Methodology
Authors
1 Department of Mechanical Engineering, B. P. Poddar Institute of Management & Technology, 137, VIP Road, Poddar Vihar, Kolkata - 700052, IN
2 Department of Mechanical Engineering, Jadavpur University, Kolkata-700032, IN
Source
Indian Welding Journal, Vol 39, No 4 (2006), Pagination: 20-31Abstract
In the present research work the reconsumption of the slag, generated during conventional submerged arc welding, has been proposed during subsequent runs by incorporating appropriate treatment and mixing it with fresh flux, with certain proportions. Experiments have been carried out by using four different levels of process parameters like welding current, flux basisity index and slag-mix percentage (percentage of slag in the mixture of fresh flux and fused slag) to obtain bead-on-plate weldment on mild steel plates. Parameters associated with bead geometry like bead height, bead width, depth of penetration have been measured for each experimental run. Heat affected zone (HAZ) geometry in terms of HAZ width has also been obtained. Assuming simple geometry of the weld bead and unit length of the job, approximate bead volume has also been calculated. All these data have been efficiently utilized to develop mathematical models for prediction of geometry and quality of weld bead as well as heat affected zone. Quadratic response surface methodology (RSM) has been applied to develop the mathematical models between predictors and responses. Based on multiple linear regressions, the coefficients of the predictors, used in the models, have been determined. Analysis of Variance Method (ANOVA), F- test and Student's t test have checked the significance of the coefficients. Reduced models with significant coefficients have also been developed. Experimental data as well as generated data have been used to represent graphically the direct and interactive effects of process parameters (slag mix% has given special emphasis in this exercise) on selected response variables associated with weld bead and HAZ. Hardness Test has also been carried out to reflect graphically, the influence of using slag-mix in SAW process on mechanical property of the weldment i.e. hardness of weld metal as well as HAZ. Finally it has been concluded that effect of using slag-mix (up to 20%) do not impose any alarming adverse effect on features of bead geometry and HAZ. Therefore, the use of slag-mix, in submerged arc welding can be recommended to apply it in practical cases, which may make the process more economical.